Cynder says the Shadows show up at midnight, so it's very likely the dungeons show up at the same time.

As for summoning method, I'd rather go with the card method in Persona 4. I mean, we already have two people who use guns so far, and it's not a good idea to have a gun [i][b]and[/b][/i] an Evoker. What if you got the two mixed up? :lol

Other places I'd like to offer for the town:
Madame Lau's Golden Pheasant Chinese Restaurant - basically run by the elderly Madame Lam and her grandchildren. Its specialty are the fortune cookies. [Mainly if you want your fortune told. Otherwise, we can just fold it into the 'mystic shop']

The YMCA Center - an old facility, but one that's provided the town with an outlet for sports and other activities. [This is for those who don't want the school to be the center of athletic options]